# Organ-Specific LC–MS/MS Phenolic Profiling and Multifunctional Antioxidant and Enzyme Inhibitory Activities of Onosma sintenisii

## TL;DR

This study explores the organ-specific phenolic compounds and antioxidant properties of Onosma sintenisii, a plant native to Türkiye, revealing that its roots are especially rich in beneficial compounds.

## Contribution

The study provides the first organ-specific LC–MS/MS phenolic profiling and enzyme inhibitory activity analysis of Onosma sintenisii.

## Key findings

- Root extracts showed the highest concentration of rosmarinic acid and strongest antioxidant activity.
- Flavonoid glycosides were mainly found in aerial parts like flowers and leaves.
- Hydroxycinnamic acids, especially rosmarinic acid, were key contributors to antioxidant and enzyme inhibitory effects.

## Abstract

Onosma sintenisii Hausskn. ex Bornm. is an endemic species of Türkiye whose phytochemical composition and biological activities remain insufficiently characterized at the organ level. The present study aimed to investigate organ-specific phenolic profiles and associated antioxidant and enzyme inhibitory activities of O. sintenisii. Ultrasonic-assisted methanolic extracts obtained from flowers, leaves, stems, and roots were analyzed using validated LC–ESI–MS/MS, and their biological potential was evaluated through multiple in vitro antioxidant assays (DPPH, ABTS, CUPRAC, FRAP, phosphomolybdenum, and metal chelation) as well as enzyme inhibition tests against acetylcholinesterase, butyrylcholinesterase, tyrosinase, α-amylase, and α-glucosidase. The results revealed pronounced organ-dependent variation in both phenolic composition and bioactivity. Rosmarinic acid was identified as the major phenolic compound in all organs, with the highest concentration detected in root extracts, which also exhibited the strongest antioxidant capacity and the most potent α-glucosidase inhibition. Flavonoid glycosides were predominantly accumulated in aerial parts. Correlation analysis demonstrated that hydroxycinnamic acids, particularly rosmarinic acid, are the main contributors to antioxidant and enzyme inhibitory effects. These findings indicate that O. sintenisii, especially its roots, represents a promising natural source of multifunctional phenolic compounds with potential pharmaceutical and nutraceutical applications.